An integrated circuit (IC) typically includes a number of semiconductor devices. One way to represent a semiconductor device is with a plan view diagram referred to as a layout diagram, or IC layout. An IC layout is hierarchical and includes modules which carry out higher-level functions in accordance with the semiconductor device's design specifications. The modules are often built from a combination of cells that can include both standard and custom cells, each of which represents one or more semiconductor structures.
Standard cells include logic devices configured to provide common, lower-level logic functions, and have at least one dimension which is the same size in order to facilitate placement into a layout. Typically, the direction of the fixed dimension is parallel to a vertical direction such that the fixed dimension is referred to as a height of the standard cell. Custom cells may or may not have at least one dimension that is the same size as the corresponding dimension of the standard cell.
To enable routing to interconnect structures to form higher-level IC modules, both standard and custom cells include conductive pins, the number of pins per cell depending on the logic function(s) being provided by the cell.